Salicylate and acetylsalicylate effect the regulation of several outer membrane protein genes in E. coli. This results in an altered outer membrane with reduced amounts of OmpF protein. As a consequence, the outer membrane is found to be less permeable to various antibiotics and the salicylate grown cells show increased resistance to diverse antibiotics. Studies on the mechanism of action of the potent antimicrobial magainins have shown that their activity is strongly concentration- dependent. Furthermore, they are very sensitive to halide ions: fluoride enormously stimulates while the larger chloride, iodide and bromide ions antagonize their activity. The human G6PD gene has been inserted in an E. coli plasmid where it can be expressed under the control of a bacterial promoter. The G6PD made in the bacteria can function in place of the bacterial gene demonstrating high conservation of function during evolution.